In accordance with certain aspects of the presently disclosed subject matter, there is provided a storage system and a method of storing data thereof. The method comprises: storing a plurality of snapshots of a certain source; assessing to at least one given snapshot an assessed value characterized by at least one of the following values and/or derivatives thereof: i. a first value characterizing the amount of unique physical data blocks associated, merely, with said given snapshot; ii. a second value characterizing the amount of unique physical blocks associated merely with a certain group of snapshots comprising said given snapshot; iii a combination of the first and the second value; and updating the assessed value responsive to a pre-defined event. The method can further comprise generating an alert when the updated assessed value and/or derivatives thereof match a pre-defined criterion; and/or providing an indication of amount of physical resources to be freed resulting from deleting at least the given snapshot, wherein said indication corresponds to the updated assessed value; and/or generating deletion recommendation in accordance with the updated assessed value; and/or automated deleting at least the given snapshot when the updated assessed value matches a threshold characterized by one or more pre-defined rigid conditions for deleting.